A man shaking hand with his stepmother's mother

Q 5: My father is married to another woman; is it permissible for me to shake hands with the mother of my step-mother?

A: You are not a Mahram (unmarriageable male relative) to the mother of your step-mother because you are Ajnabi (a man lawful for the woman to marry) to her. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.